A DVB-T signal may use multiple carriers based on orthogonal frequency division multiplexing (OFDM). A data frame of a DVB-T signal may include 68 OFDM symbols, each including 1705 active carriers when in a 2K mode or 6817 active carriers when in an 8K mode. Each symbol includes pilot carriers used for synchronization, mode detection, and channel estimation, and locations of the pilot carriers may be predetermined.
FIG. 1 is a block diagram of a conventional DVB-T receiver 100. Referring to FIG. 1, conventional DVB-T receiver 100 includes a radio frequency (RF) module 110, a demodulator 120, a fast Fourier transform (FFT) unit 120, a symbol timing recovery and carrier recovery (STR & CR) unit 140, an equalizer 150, and a decoder 160 for forward error correction. An output of the decoder 160 is provided to a signal processing unit to generate signals for display and audio output. The demodulator 120 removes a symbol timing offset and a carrier frequency offset (detected by the STR&CR unit 140) from a DVB-T digital signal generated by the RF module 110 and demodulates the DVB-T digital signal.
The demodulator 120 receives a manually set spectrum inversion signal Spectrum_Inversion and operates in a spectrum inversion mode or a non-spectrum inversion mode according to a logical state of the spectrum inversion signal Spectrum_Inversion. That is, the spectrum inversion signal Spectrum_Inversion indicates whether (or not) the DVB-T digital signal received from the RF module 110 is a spectrum-inverted signal. The demodulator 120 demodulates the DVB-T digital signal using oscillation signals generated for the manually set spectrum inversion signal Spectrum_Inversion. Here, an inconvenience may result because a user may need to determine whether a spectrum of the DVB-T digital signal is inverted and set the spectrum inversion signal Spectrum_Inversion according to the determination.